Constructing a Crystalline NiCo₂O₄/Amorphous NiFeO(OH) Heterostructure for Boosting Electrocatalytic Water Oxidation

The construction of efficient oxygen evolution reaction (OER) electrocatalysts is significant in enhancing the efficiency of electrocatalytic hydrogen production. Heterostructure amorphous–crystalline materials have advantages with good conductivity and increased exposure to active sites. They have also been developed as prospective OER catalysts in an alkaline medium. This study synthesized an amorphous–crystalline composite heterostructure catalyst, NiCo2O4@a-NiFeO(OH), via a simple hydrothermal and impregnation treatment. Structural characterizations indicated that the NiCo2O4 scaffold exerts a crucial function in determining the morphology of amorphous NiFeO(OH). The catalyst demonstrated outstanding OER activity, requiring overpotentials of only 219.6 mV and 260.8 mV at current densities of 10 mA cm–2 and 100 mA cm–2, respectively. The enhanced OER performance is attributed to the synergistic electronic interactions within the heterostructure, combined with increased surface hydroxylation, which identifies Ni species as the key active sites for the OER. This study underscores the potential of heterostructure design in advancing electrocatalytic OER performance.